It is common in many processing technologies to utilize articles automatically fed from a group of articles or to automatically feed articles to or from a group. Feeding systems and stacker systems discussed herein are frequently an integral part of mail piece inserting systems and mail piece sorting systems.
In applications for feeding articles from a group, it can be very desirable to maintain suitable pressure on the group to facilitate and optimize feeding of items from the group. In sheet processing in particular, it is common to provide a group or even a stack of sheet articles and to pull or feed articles from the group either in smaller groups or one by one. Such groups in sheet processing can include, for example, envelopes of any size, insert material for feeding into envelopes or any other suitable sheet material. Groups of sheet articles can be used in sheet processing for feeding of sheet articles from the group or to the group. Envelopes or other sheet articles can be fed from a group of envelopes, which requires pressure maintenance on the group during the feeding process. In a similar manner, envelopes or other sheet articles can be fed to a group of the sheet articles, which also requires pressure maintenance during the feeding process to make room for additional sheet articles. As can be appreciated by those of skill in the art, the use of either a feeding mechanism or a stacker input mechanism imposes pressure control requirements for the group.
When processing envelopes in particular, a conventional technique for processing the envelopes involves holding the group of envelopes where they are all in a vertical orientation in a group and where envelopes can be removed for feeding from one end of the group. As envelopes are removed from the group, it is desirable to keep pressure on the group of envelopes to continue the process. One way to keep pressure on the group of envelopes is to move a belt under the group of envelopes to adjust and maintain desired pressure on the group. Also, some techniques use a mechanism such as a paddle to push against one end of the group of envelopes to apply pressure. In the past, movement of the belt or paddle mechanism has been set to occur during processing of the envelopes at periodic time intervals, such as for example once every 15 milliseconds, to maintain pressure on the remaining envelopes in the group. For a stacker implementation, the process is reversed so that the belt or paddle must be moved every time an envelope is added to the stack to maintain a constant stack pressure.
In light of the above, there remains much room for improvement, particularly with regard to sheet processing, for a more dynamic method for maintaining pressure on a group of articles while processing or removing articles from the group.